It's the overall gameplay direction that I don't like, the maps are small and ballistics do ridiculous damage, so defence goes out the window and it ends up feeling even more of a spamfest than any other arena shooter, which I feel is the complete opposite of why people liked UT2004 and the defensive heavy/hitscan meta it has. I'm tempted to blame multi-platform for why it ended up the way it did in that regard, combat is just resolved so fucking quickly.
That was intentional. UT2k4 was so defensive with dodge jumping and Shock Rifle primary was SO GOOD it actually broke the entire game. In addition, in UT3, projectile weapons actually have LESS splash damage than in 2k4 and MORE direct damage, meaning they reward accuracy more. Shock Combos also have a smaller blast radius, do far less damage, and are much harder to hit than in 2k4. Bearing this in mind, UT3 is actually the least "spammy" of any of the UT games.
The high damage is also intentional. You are supposed to die fast in Unreal Tournament until you get stacked. In 2k4, most of the weapons were really pathetically weak and it took forever to kill anyone. This was one of the main complaints many classic UT players had against 2k3, and 2k4 didn't really fix it.
Shock Rifle was so good in 2k4 it invalidated most of the weapons. This problem was made worse by dodge jumping. Now, not only is the Shock Rifle far and away the best weapon in the game, Rockets and Flak are useless because its impossible to hit anyone with them. High level 2k4 duels basically involved entirely around controlling the Shock Rifle and Lighting Gun, because none of the weapons were actually good enough to kill you. The term "Shock Tape" was coined in UT2k4 because all you did to kill people was shoot them with Shock primary and then use the knockback to gauge where they were going to land next and kept doing it until they were dead. The running joke was you could play UT2004 by scotch taping down your mouse button and using only the Shock Rifle. This was embarrassingly close to the truth.
It seems like when a lot of people criticize UT3 they don't really understand why the changes were made to that game and how it works on an engine level. 2k4's entire metagame revolved around one weapon, there was no way from a balance perspective Epic wasn't going to change things.
I realize people love UT2004 and for many people it was their first Unreal Tournament game, but its completely busted from a balance perspective and there was no way Epic was going to build off that type of gameplay for UT3.